NOT T1IS RUOIXT HAS TO THE BEEN RELEASED EXECUTIVE DIRECTORS RESTRICTED RETURN TO ~ CIRCULATING COPY RI EBE RETURNED To ARCHIVES REPORTS DESK

Public Disclosure Authorized WITH N ONE W Eli1 r art was prepared for use within the Bank. It may not be published nor may it be quoted as representing the Bank's views. The Bank accepts no responsibility for the accuracy or completeness of the contents of the report.

INTERNATIONAL. BANK FOR RECONSTRUCTION AND DEVELOPMENT Public Disclosure Authorized

RIVER BASIN DEVELOPMENT

CEYLON Public Disclosure Authorized

May 1961 Public Disclosure Authorized

Department of Technical Operations April 20, 1961

REPORT BY BANK MISSION ON RIVER BASIN DEVELOPMENT, CEYLON

Terms of Reference

A Bank Mission consisting of Messrs. R. A. Wheeler, Christian Finne and Albert R. Johnson visited the Island of Ceylon for about five weeks from the end of January, 1961 to the first week in March. The terms of reference for the Mission were contained in a letter from the Bank to the Ceylon Govern- ment, dated December 28, 1960.

The general purpose was to make a study of river basin development covering all aspects of such development, including power, irrigation and flood control. In particular, the Mission was requested to review all studies so far made of the various river basins, to determine what further studies should be undertaken together with recommendations on how they should be 4nitiated and estimate of time required for their completion, and to sub- mit recommendations concerning priorities between projects for development of the various river basins,

Reports reviewed

Reports were available on multipurpose projects in the Mahaweli Ganga: and Walawe Ganga Basins and a preliminary statement was presented on the Kelani Ganga Basin. Reports on projects for the primary purpose of irrigation were available in the Aruvi Aru and Kala Oya Basins. These were reviewed by the Mission and the basins inspected.

The Mission also visited the power projects in the Maskeliya Oya and Kehelgamu Oya Basins and the partially completed multipurpose develop- ment project in the Gal Oya Basin. In addition, the Mission reviewed the summary table that was prepared by the Ceylon Department of Irrigation con- cerning projects for irrigation in seventeen other river basins. The list of reports reviewed by the Mission is given in Appendix 1.

Mahaweli Ganga Diversion Project

The Mahaweli Ganga Basin has the largest watershed of the island (4034 sq. mi.), being more than three times the size of the next watershed in size (1268 sq. mi.), the Aruvi Aru Basin. The average annual discharge of the Mahaweli Ganga-is also one of the two largest, 6 million acre feet, the Kalu Ganga also being about the same volume.

A preliminary report on the Mahaweli Diversion Scheme has been prepared by ICA. It deals with the feasibility of diverting a substantial portion (about 1.6 MAF) of the Mahaweli Ganga waters near Kandy and conveying -2 - the water to the North Central Province (NGP) for irrigation and genera- tion of electrical energy at favorable locations. Some flood-protection benefits will be provided in the Kandy area, and additional water will be made available for domestic uses in the cities of Kandy and Anuradhapura. However, these benefits are small compared to the others and are not in- cluded in the benefit-cost ratio.

It is a large project consisting of the construction of two dams and reservoirs, a diversion dam on the Mahaweli, four major power plants having a total of 243,000 IV installed capacity, the NCP Canal 124 miles in length, the irrigation of 215,000 acres to produce two crops per year in the Anuradhapura District of the NCP, the irrigation of .10,000 acres to produce two crops per year in the Elahera-Kantalai and Angamedilla systems and the construction of three minor canal power plants in the lower reaches of the N-C-P Canal.

This project will require an ultimate investment of about 1203 million rupees (US$ 250 million) in capital works, of which 613 million rupees (US$ 130 million) is foreign exchange. It is estimated that it will produce 1440 million KWH of marketable electric energy of which 1320 million XWH will be firm. The benefit-cost ratio has been estimated by ICA at 2.3 to 1.

The project can be constructed in stages. The first stage would provide the benefits of irrigation for 80,000 acres, of flood control and of 90,000 KW of firm power, estimated to cost a total of 421.5 million rupees (US$ 88 million) of which 186.4 million rupees (US$ 39 million) is foreign exchange.

A more detailed description is given in Appendix No. 2.

This preliminary report on the feasibility of the diversion scheme was prepared by competent and experienced engineers of the ICA. They received the cooperation and assistance of Ceylonese engineers from the irrigation and electrical departments. The report is satisfactorily presented in sufficient detail to show that favorable results can be ex- pected, that the hydroelectric potential is substantial and can be developed in stages progressively with the demand and at reasonable cost and that a substantial part of the area to be irrigated is developed and needs primarily supplemental water supplies. Land classification of reconnaissance type has already been made of the lands to be irrigated. The farmers in the North Central Province have had considerable experience with irrigation so that increased food production from irrigation is likely to be both greater and more certain than from completely new irrigation areas. Assured water for irrigation in the NCP will make possible substantial gains from early adoption of improved techniques in rice production on existing areas. Substantial areas of land suitable for new irrigation farming are avail- able in the NOP and can be developed without interference with the early gains from providing water to the presently irrigated areas with a short water supply. - 3-

These cons.derations justify the conclusion that the project is ready for the necessary further detailed engineering studies and for prepara- tion of the plans for the first stage which, it is estimated, would require about a year and a half. The necessary further engineering studies are now continuing under the supervision of the ICA and Ceylonese engineers. The plans for this project are further advanced than for any other project that was reviewed by the Mission.

The effect of the proposed diversion of 2500 cusecs from the Mahaweli Ganga near Kandy upon the planning for the Mahaweli Ganga Basin below the point of diversion is being studied further by the ICA engineers and the Ceylon Irrigation Department. In the summary table prepared by the Ceylon Irrigation Department, it was stated that the diversion to the basins in NCP was economically justified because of the much greater areas of existing irrigated lands in these basins than in the lower Mahaweli Ganga Basin.

Walawe Ganga Basin

The Walawe Ganga, located in the Southeastern part of Ceylon, has a drainage area of 954 square miles and an average annual discharge of about 1.6 million acre feet. It is the fifth river of Ceylon in volume of dis- charge.

A general survey of this basin was carried out by the Photographic Survey Corporation of Canada under the Colombo Plan assistance program. The report was completed in July 1960. The purpose of the survey was to provide an inventory of geology, land forms, soils, land use, forest cover and hydro- logy and to make suggestions and recommendations concerning future use of the land and water resources.

The report points out the lack of hydrologic data and information on floods and recommends the installation of additional discharge and rain gauging stations. It proposes a four-stage program of development and is described in greater detail in Appendix No. 3.

Stage 1 includes the construction of a storage dam on the upstream Walawe Ganga, a diversion tunnel to a forebay reservoir on the Diyawini Oya and a power plant on the north bank of the Katupal Oya at the foot of a steep escarpment. A dam constructed across the Katupal Qya would create a regula- ting reservoir for the irrigation canals. These works correspond to the Samanala Wewa project which is described in Appendix No. 4. Stage 1 would also include a diversion dam on the Walawe Ganga below its confluence with the Katupal Oya as well as the necessary irrigation canals.

Stage 2 includes a storage dam on the Weli Oya, and irrigation canals; stage 3, storage dams on the right bank tributaries, Yuda Oya and have Rakwana Ganga, with irrigation canals. The flows of these tributaries not been computed and no field investigations have been made of possible dam sites. -4- Stage 4 includes a storage dam at one of four possible sites on the lower Walawe Ganga above Embilipitiya to provide balancing storage for irrigation of the coastal area. This stage can only be developed after plans for the upstream works have been completed so that the water supplies avail- able in the lower region can be evaluated. The Uda Walawe Project which is described in Appendix No. 5, corresponds to Stage 4 and was developed before the Canadian study became available.

The survey report concludes that the possible development looks sufficiently promising to justify more detailed studies which should include, in particular, the evaluation of the hydrologic information obtained from the additional gauging stations, detailed investigations of possible dam sites, topographical surveys of lands to be irrigated, land classification survey and operational studies to establish the necessary coordination of water releases for power production and irrigation.

Kelani Ganga Basin The Kelani Ganga discharges into the sea at Colombo. It has a drainage area of 885 square miles and an average annual discharge of 5 million acre feet.* In volume of discharge, it is the third river in Ceylon, after the Mahaweli Ganga and Kalu Ganga. The river is subject to flooding in the Colombo area. The maximum flood, 220,000 cusecs at Colombo, occurred on August 17, 1947 and caused damages estimated at 10 million rupees of which about 8 million rupees were direct damages. Late in 1959, the Ceylonese and Soviet Governments entered into an Agreement on Economic Cooperation and Technical Assistance for the study of a scheme of flood control and water resources development of the Kelani Ganga. The work was assigned to Giprovodkhoz, the Design and Research Institute for Land and Water Development of the Ministry of Agriculture of the Soviet Government. The agreement provides for the study of a multi- purpose development for flood control, power production, development of irrigation in the Kelani Ganga Basin and also for the diversion of the Kelani Ganga waters to the north into the dry zone for irrigation. The primary purpose to be served by the development scheme is flood control. Soviet technicians arrived in Ceylon in the early months of 1960 and after completing their planned field work and collection of data with the cooperation and assistance of Ceylonese engineers, returned to Moscow in October, 1960 where they will prepare their plan and report which is expected to take one year. Ceylonese technicians will join them in Moscow during the second quarter of 1961 to participate in the preparation of the plan. Giprovodkhoz prepared an "unedited report on contemplated measures" which contains only a very preliminary general discussion of various alterna- tives without sketches, cross sections, capacities, estimates of cost or con- clusions. The "unedited report" states that it is expected to provide -5-

flood protection 'oy maans of a combination of levees and reservoirs, to develop hydro-electric power at the river regulation reservoirs and to divert surplus waters to the north for irrigation of 100,000 to 200,000 acres. Additional details are given in Appendix No. 6.

Gal Ova Basin

The Gal Oya, located in the eastern part of Ceylon, has a drain- age area of 700 square miles and an average annual discharge of one million acre feet. In volume of discharge, it is the seventh river of Ceylon.

The Gal Oya Project is presently the country's largest multiple- purpose development project and is operated by the Gal Oya Board, an autonomous agency of the Government. Through the development of nine deten- tion reservoirs in the Gal Oya Basin, the project is to provide flood con- trol, irrigation, hydro-electric power and new settlement opportunities in agriculture and industry.

Work was started in 1949 with construction of the main detention reservoir on the Gal Oya with 770,000 acre feet of capacity. This reservoir, along with other smaller reservoirs, now supplies water for irrigation of about 75,000 acres of rice and a 5,000 KW power plant. A 3,000 acre sugar cane plantation has been established along with a sugar factory for 30,000 tons of cane sugar. Expansion of the area in cane to 9,000 acres by 1963 is contemplated. Other industries in the Gal Oya development include a brick and tile factory, a rice mill, a saw mill and related smaller industries.

Approximately 11,000 families are now engaged in agriculture and industry in the Gal 0ya development area.

Almost Ra. 500 million have been invested in the Gal Oya project at this time. Gross annual returns to agriculture and industry have been reported at about Rs. 30 million, or about 6% on the total investment. This is a relatively low gross rate of return, so that the project may not be a financial success unless a very high value is placed on the settlement opportunities that have been provided. Present plans envisage the irriga- tion of an additional 50,000 acres along with the clearing of highland for village and community development. The project is expected to be completed by 1965, with the total estimated cost of Rs. 883 million.

Maskeliva Oa Power Project

A feasibility engineering study of power development on the Maskeliya Oya has been prepared by Hydrotechnic Corporation and Engineering Consultants Inc., under a contract between ICA and the Ceylonese Government. Their report which was completed in May, 1960, proposed a development con- sisting of an upstream storage dam at Mousakelle, a power plant 3* miles downstream at Theberton, an extension of the existing Laksapana Power Plant -6 -

and a downstream power plant below Laksapana at Morahena, including a fore- bay pond and two diversion dams, intake canals and transmission lines. A revision of the plans for the Morahena plant, moving it further downstream to develop additional head, is now being studied. Unit cost for the total installation would be US$ 240 per Wd and for the Morahena plant at the new location, US$ 200 per KW.

A description of the Maskeliya Oya Power Project is given in Appendix No. 7.

Aruvi Aru Basin (Malwatu-Qya Basin)

The Aruvi-Aru, located in the northwestern part of Ceylon, is called the Malwatu Oya in the upper reaches. It has a drainage area of 1,268 square miles which is the second largest watershed in Ceylon.

A multiple-purpose project called the Malwatu Oya Reservoir Project providing the benefits of irrigation, flood control, power development and municipal supply has been under study by the Ceylon Irrigation Department for some time. In February 1958, a contract was concluded between the Ceylon and USSR Governments in conformity with their Agreement on Economic Cooperation and Technical Assistance, to study this project. The design work was given to Giprovodkhoz, the Design and Research Institute for Land and Water Develop- ment of the Ministry of Agriculture of the U.S.S.R. With the cooperation and assistance of Ceylonese engineers, Giprovodkhoz made field investigations, collected data and information and returned to Moscow where a report was prepared in 1960.

The report provides for a dam located upstream at Kappachichi. The catchment area above the site is 819 square miles and the average annual discharge at the site is 312,000 acre feet. The dam is an earth structure 2.42 miles in length and 92.5 feet above the river bed. It is provided with a concrete, gated spillway. The proposed reservoir of 282,000 acre feet of usable storage includes additional capacity sufficient to detain the highest flood of record. It is also proposed to construct an 800 KW hydro-electric plant which however, would require a diesel plant of equal capacity to provide a supply of firm power. The reservoir will also provide a municipal supply of water to.the town of Cheddikulum. It is proposed to irrigate 32,000 acres including 20,000 acres of existing irrigated land but adequate water supply is not available in all years.

The total estimated cost of the Project is Rs. 51.6 million (US$11 million). Tentative cost allocations indicate that the construction cost for irrigation amounts to Rs. 1125 (US$ 235) per acre and for power, Rs. 2560 (S' 530) per installed kilowatt. No estimate is submitted as to the foreign exchange portion of the total cost.

Kala Oya Basin

The Kala Oya, located in the northwestern part of Ceylon, has a watershed of 1044 square miles. Existing in the Basin are over 300 working - 7 -

tanks, mostly of small size. There are several large existing tanks, one of which, the Kala Wewa in the upper part of the Basin will receive in- creased supplies from the Mahaweli Diversion Project. The proposed plan of development provides for four new reservoir schemes of which only one, Rajanganga, has been presented for consideration. It is outlined in a memorandum of three typewritten pages dated December 22, 1960, entitled Rajanganga Reservoir Scheme, and was apparently prepared in the Ceylon Irrigation Department. No other data were presented.

The catchment area of the proposed Rajanganga Dam site is 622 miles of which about 325 square miles are cut off by the present Kala Wewa thereby reducing the effective catchment area to 297 square miles. With an average annual rainfall of 62 inches, the estimated annual yield is 104,000 acre feet. The highest estimated flood flow at the dam site is 80,000 cusecs,

The Rajanganga Project is primarily an irrigation scheme but provides partial benefits of flood control and power development. The water supply is estimated to be sufficient to irrigate 20,000 acres for rice. Provision is made to handle a flood with peak discharge of 50,000 cusecs. It is also proposed to develop 750 EW of hydro-electric power by means of three turbines with an equal number of standby thermal units. The dam consists of a central concrete section 1175 feet long flanked by two earth embankments 4530 feet and 7355 feet long respectively, making total length of 13,060 feet. The concrete section will have an overfall section and also a section of radial gates for flood control.

The project report is too incomplete to permit a judgment on its merits.

Additional River Basins

The Ceylonese Government submitted a summary table showing the proposed developments in 19 river basins, all of which except in two basins, are for the primary purpose of irrigation. These two, the Mahaweli Ganga and Walawe Ganga Basins, in addition to providing for the benefit of irriga- tion, also provide for the development of power.

The Mahaweli Ganga Basin below the point of diversion near Kandy, of the proposed Mahaweli Diversion Scheme, will need to be restudied, taking into consideration the supplies available after the proposed diversion of 2,500 cusecs into the North Central Province. The Mahaweli Diversion Scheme and the Walawe Ganga Basin are subjects of separate reports.

The remaining proposed developments in 17 river basins are not multipurpose projects but are primarily for irrigation. Several of them will be affected by the proposed Mahaweli Diversion Scheme and the Walawe Ganga Basin Comprehensive Plan, and it will be necessary to reconsider the irrigation plans for these smaller streams. -8-

Determining the extent to which irrigation development in the various basins under investigation is economically feasible would require considerably more information than is presently available. The Mahaweli Diversion Project report indicates that the project would supply water for 315,000 acres at an initial cost of Rs. 2078 per acre; however, a substantial portion of the area has, at present, a partial water supply, and in many years a full water supply. Thus for the additional, or new, areas to be irrigated it can be expected that the irrigation project costs will range from Rs. 2500 to Rs. 3000 per acre. In addition to the project costs, the costs of clearing and settlement average around Rs. 1000 to Rs. 2000 per acre so the total per acre costs range from Rs. 3500 to Rs. 5000. When these investment costs are amortized over 50 years at 4 per cent interest and including a cost for maintenance, the annual cost will fre- quently be more than Rs. 250 per acre. The value of a single crop of paddy, computed on the basis of Rs. 7 per bushel and 40 bushels per acre would total Rs. 280 per acre. With the double cropping proposed the annual crop might yield around Rs. 500 per acre with some increased costs for opera- tion and maintenance.

Thus about one-half the annual gross value of paddy production would be absorbed by capital and related costs. It is doubtful whether the remainder would be sufficient to cover the farm production costs and allow any reasonable return for the operator's labor. While these computations are rough, they indicate the need for a thorough analysis of the major seg- ments of basinwide projects in order to select those likely to produce favor- able (or least unfavorable) returns.

Selection of Lands to be Irrigated

Insufficient field investigation is a general comment regarding the irrigation aspects of the multiple-purpose project reports that have been reviewed. Considerable field work was done for preparation of the Mahaweli Diversion Project report, but the land classification can be con- sidered only of a reconnaissance grade. This may be adequate for the presently irrigated lands that will receive supplemental water from the project, but a more detailed land classification should be made for the new lands to be irrigated. For the proposed projects in the Walawe Ganga Basin there has been no field investigation of the lands proposed for irrigation. The presently available reports are merely "desk appraisals" based on limited information on topography and cover along with assumed ebopping patterns, yields and canal costs. Local planning officials recognize the need for better field investigations as indicated by the Chief Planning Officer for the Gal Oya Project in a recent statement as follows: n. . . Planning for Land Development in the Valley has been handicapped by lack of suitable plans showing the soil types and vege- tation in the area taken up for development. In consequence it may well be that we are wasting the available resources by over irrigating certain lands or irrigating lands which are unsuitable for cultivation.n -9-

Control of Water Ue

Field observations and informed reporters indicate that the presently available water is frequently used very inefficiently and that there will be need for more effective control over the use of water to be supplied by major irrigation facilities. Presqnt water duties appear excessive. A probable reason is that the water users are charged only a nominal amount of Rs. 5 per acre for the water service, and frequently this is not paid. Water use could be controlled through a charge in accordance with the amount of water used or through allotments. In any event the current nominal charge of Rs. 5 is far less than the annual operation and maintenance costs and should be raised so that the water users will not consider water as a free-good. Consideration should also be given to the establishment of local organizations that could assist in administering the water control programs.

Policies for Land Development and Settlement Opportunities

Ceylon imports substantial quantities of rice and other food products, while the available land and water resources are sufficient to permit substantial expansion of the area of crop production. There has also been a serious shortage of employment opportunities and new agricultural settlements have been undertaken. Government programs for irrigation have, therefore, been oriented towards providing both (1) expanded production of the required food supplies and (2) providing new settlement opportunities. The chief limitation of the scope of this program is the high cost to the Government as compared with the economic gains from the increased crop production and the financial gains cf the settlers. The Government policies on new irrigation projects need to be reconsidered, particularly with regard to the adequacy of the size of the settlement units being provided, the selection of settlers based on qualifications rather than need, the extent to which repayment of government costs should be required and the possi- bility of assigning responsibility for project management to basin or local groups. Consideration might also be given to the desirability of emphasizing alternative means of increasing production more quickly than by new land settlement. A substantial quantitative increase in production from existing paddy lands can probably be achieved more quickly and at less cost than through new land development. The construction of large multiple-purpose projects would require substantial new investment capital and the country's ability to finance these investments would have to be reviewed in light of other capital requirements.

Irrigation Projects and the Rice Subsidy

The Government of Ceylon has tried to stimulate rice production by a government guaranteed price of 12 rupees per bushel. Through this program, from one-third to one-half of the rice crop has been sold to the government at the subsidized price and in recent years has cost the govern- ment from 85 to 100 million rupees annually. Assuming continuation of this program in the future, and about the same proportion of the crop being sold - 10 - to the government, the increased rice production expected from the proposed Mahaweli Diversion Project will result in an increased rice-subsidy cost of 60 million rupees annually, and other projects would have similar effects.

Reports have indicated that the rice subsidy scheme has not stimu- lated production in proportion to its cost. Other means of stimulating pro- duction might therefore be more effective and less expensive. An incentive program designed to encourage adoption of improved practices would appear more effective in achieving increased production. Payments or subsidies could be granted for fertilizer applications, planting methods, soil and water management practices or production improvement practices.

In view of the presently large rice subsidies, amounting to Rs, 200 per acre per year where a 40 bushel crop is grown, it seems incredible that the government does not collect more than Rs. 5 per acre for irrigation water service. The Minister of Agriculture clearly indicated that suggestions for substantial reduction in the subsidies presently granted to the rice growers would be politically unacceptable at this time. The Minister of Finance, however, expressed the view that the country could no longer afford some of the high subsidy measures and particularly mentioned the high government cost of the colonization schemes with 4 and 5 acre land allotments and no repayment.

Power Supply in Ceylon

The main power system in Ceylon is operated by the Department of Government Electrical Undertakings (DGEU). It serves the eastern and central part of the country, including Colombo and Kandy. outside this central system there exists a number of local supplies served mainly by diesel units. The largest of these, which is also operated by DGEU is in Jaffna, served by a 4 MW diesel plant.

The present and estimated peak load of the central system and present and planned available capacity are as follows;

Year ending Peak Load Effective Effective Firm September 30 MW Plant Capacity Plant Capacity 2/

1960 58 74.5/ 62 1961 67 74.5 62 1962 73 99. 74.5 1963 89 124.W-, 99.5 1964 105 174."W 149.5 1965 116 174.5 149.5 1966 132 174.5 149.5 1967 148 174.5 149.5 1968 166 174.5 149.5 1/ With largest unit out of operation. 2/ Laksapana hydro 50 MW, Stanley Steam 7.5 MW, Pettah diesel 17 MW. Grandpass I 25 MW. Grandpass II 25 MW. Norton hydro 50 MW. - 11 -

The load -crecast was prepared in connection with the Bankts appri-- sal of the present expansion of the DGEU system. It has been assumed that domestic and commercial loads will continue to increase at the rates experienced over the last five years. To this has been added the expected load of a number of new industrial plants and various other prospective loads. The new industrial load is estimated to increase from 1.5 MW in 1961 to 17 MW in 1965 and 36 MW in 1.967 after applying a diversity factor of 1.3. A few of these industrial schemes are under construction but most of them are in the planning stage and their financing presents considerable problems. The possibility exists, therefore, that the industrial load might increase at a slower pace than now planned.

On the other hand, DGEU has never had sufficient capacity reserves to promote sales of power. Within the service area exist a number of diesel installations serving tea and rubber estates and industrial plants. Total capacity of these plants has been estimated to be between 50 MW and 100 MW. Undoubtedly a substantial part of this load could over a period of time be connected to the DGEU system.

While the estimated increase in peak load might be on the high side, it is reasonable to plan for additional capacity to be added by 1967 or at the latest in 1968,

The addition of a new hydro plant is estimated to require at least 6 years including 2 years for preparation of detailed design and specifica- tioiis as well as calling for and receiving bids and 4 years for construction. A decision on which project to select would therefore have to be made during 1961.

The most attractive project from the point of view of power supply is undoubtedly the revised Morahena project. This plant, wiLtaout the pro- vision of upstream storage on the Maskeliya Oya, would have a-o installed capacity of some 50 MW and could be constructed at an estim,';-d cost of Rs. 49 million ($10 million) including Rs. 28 million ($5.8 r,lliorn) in foreign exchange.

It is understood that the Minister of Agriculture, lands and Power has recommended to the Cabinet that negotiations with Yugoslavia should be authorized regarding the engineering and construction of this project, to utilize a credit of Rs. 56 million offered by Yugoslavia under its 1958 trade agreement with Ceylon.

If the Government decides to go ahead with the execution of the Morahena plant, it would provide sufficient capacity to meet demand until about 1970. In this case it would be premature to make a decision at present about further expansion. It would depend on the increase in load over the next two years, the progress on the industrialization program and on the decisions made with respect to the construction of multipurpose schemes which would also provide water for irrigation. -12 -

Priorities betJen _.a2ects

The Mission's terms of reference indicate that recommendations should be made concerning priorities between projects for development of the various river basins. In order to have objective measures to guide the establishment of priorities it is essential that the various basin projects be planned and evaluated on a comparable basis. Such project infornation was lacking in the various multiple-purpose project reports that were available for review, and the basic information available was not sufficient for development of comparable analyses. Consequently, the Mission's recommen dations of priorities are based lare2L on g_=I Bthe r6v_i_e_w of all available reportsTm-a i-TnfbTaion along with limited field inspection of the principal siEes and areas involved. The recommendations should therefore be considered subject to review and possible modification as new surveys, plans and analyses are completed and the availability of both local and foreign funds for the capital investment has been determined.

The Mission recommends that first priority be given to the formula- tion of plans for development of the Mahaweli Diversion Project for the following reasons-.

a. Plans for this project are further advanced than for any other project that was reviewed and show that favorable results can be expected.

b. The project can be developed in stages.

c. A substantial block of firm hydroelectric power would become available.

d. A substantial part of the irrigation service ar?ea from Mshaweli is developed and needs primarily supplemental water supplies whereas the Walawe Basin would require both costly clearing and colonization. The Mission believes that Ceylon's colonization program has been costly and should be reappraised before being extended under new major irrigation projects.

e. A reconnaissance land classification has been made of the lands to be irrigated from Mahaweli in the NCP while no similar work has been started in any other basins.

f. The farmers in the NC? have had considerable experience with irrigation so that increased food production from irrigation is likely to be both greater and more certain than from completely new irrigation areas.

g. Assured water for irrigation in the NCP will make possible substantial gains from early adoption of improved techniques in rice produc- tion on existing areas.

h. Substantial areas of land suitable for new irrigation farming are available in the NCP and can be developed without interference with the early gains from providing water to the presently irrigated areas with a short water supply. The Mission makes no specific recommendations as to second or third priority projects but suggests that project planning in the Walawe Ganga basin (Samanala Wewa and Uda Walawe) should not be completed until a basin survey of the available water supplies has been completed along with a classification of the lands proposed for irrigation. When these surveys have been completed, the present feasibility studies should be revised and completed. Water supply and land classification surveys should be included in other basin investigations such as the Kelani Ganga, the Malwatu Oya Reservoir Project on the Aruvi Aru and the Rajanggnga Reservoir on the Kala Oya.

Recommendations

a. For multiple purpose development of river basins, the Mission recommends that first priority be given to the continuation of the detailed engineering studies on the Mahaweli Diversion Project and for preparation of plans for the first stage. It is estimated that this work will require one and one-half years and that construction would require four years.

b. Project planning in the Walawe Ganga Basin should await the completion of a basin survey of available water supplies and adequate land classification.

c. Water supply and land classification surveys should be in- cluded in other basin investigations, such as the Kelani Ganga, the Malwatu Oya Project on the Aruvi Aru and the Rajanganga Project on the Kala Oya.

d. For power only, the Mission believes that the studies of the Morahena Project should be completed and the detailed drawings prepared.

cc: Area Department (2) Technical Operations Department (2) C.F. (1) A.R.J. (1) R.A.W. (1) LIST OF REPORTS REVIEWED BY MISSION-

River Basin Reports Source

Mahaweli Ganga Mahaweli Ganga Diversion U.S..M. and Ceylon Project Irrig. Dept.

n n Government's Proposed Ceylon Irrigation De- Development (Kantalai partment Basin)

Walawe Ganga Samanala Wewa Project Hydrotechnic Corp. and Engineering Consul- tants, Inc.

n nResources of Walawe Ganga Basin Photographic Survey Corp.

I I Uda Walawe Project Engineering Consultants, Inc.

n nLower Walawe Ganga at International Engr. Co. Embilipitiya

n nWalawe Region - Government's Ceylon Irrigation Proposed Development Department

Kelani Ganga Kelani Ganga Project Giprovodkhoz, USSR

Economic condition of flood Ceylon Irrigation control and utilization Department of water potential of the Kelani Ganga

Gal Oya Gal Oya Project Gal Oya Board

n n Government's Proposed Ceylon Irrigation Development Department

Maskeliya Qya Maskeliya Oya Project Hydrotechnic Corp. & Engineering Consul- tants, Inc.

Aruvi Aru Malwatu Oya Reservoir Project Giprovodkhoz, USSR

" " Government's Proposed Ceylon Irrigation Development Department

Kala Oya Rajanganga Reservoir Project Ceylon Irrig. Dept. List of 17 river Governmentts Proposed Ceylon Irrigation basins (see Development Department next page) LIT OF 17 RIVER BASIMS RECOMNENDED BY THE CEYLON IRRIGATION DEPARTMENT FOR THE GOVERNEN'S PROPCSED DEVELOPNEN (Statement of Proposed Development under Proposed and Existing Reservoirs)

Kala Oya Piramenthal Aru Karakarayan Aru

Heda Oya Maduru Oya Nay Aru

Mundendi Aru Menik Ganga Moderagam Aru

Kirindi Oya Kumbukkan Oya Manal Aru

Yan Oya Wila Oya Malala Oya Dedura Oya Kiramu Oya Appendix 2

MAHAWELI GANGA DIVERSION SCHEME

Mahaweli Ganga

The river rises in the central area of Ceylon at elevation over 7,000 feet and flows for a distance ofppme 120 mile1qstoyards the north and east and discharges into the sea near the town of Trincomalee. The total drainage area is 4,034 square miles. Average annual run-off of the river at Kandy is about 2 million acre feet and for the over-all basin about 6 million acre feet, Maximum flood at Kandy has been estimated at 165,000 cs.

The most important upstream tributary is the Kotmale Oya with a drainage area of 205 square miles and 843,000 acre feet average annual run-off.

The largest downstream tributary is the Amban Ganga with a drainage area of 238 square miles and 561,000 acre feet average annual run-off,

Mahaweli Diversion Scheme

The Mahaweli Diversion Scheme has been developed by a team of U.S. engi- neers under a contract between the Ceylonese Government and ICA. The Scheme forms a part of an over-all plan for the development of the Mahaweli Basin. It includes the regulation of the Kotmale Oya, an upstream tributary of the Mahaweli, at a point 7 miles upstream of the town of Ulapane, the diversion of a substantial portion of the Mahaweli Ganga waters at a point 2 miles up- stream of Kandy, and conveying the water to the North Central Province (NOP) for irrigation and generation of electric power. Additional benefits include flood protection and possible supply of drinking water to Kandy and Anuradhapura. The Diversion Scheme would be operated to pass a sufficient amount of water down the Mahaweli Ganga to assure the supply of water to possible irrigation of areas in the downstream part of the Basin, These areas are at present mostly covered by jungle and their suitability for development is being studied at present.

Upstream Storage

The damsite is located at Nugawela on the Kotmale Oya, 5 miles upstream of its confluence with the Mahaweli Ganga. The dam is designed as an earth and rock fill structure, with a height of 350 feet above the river bed, A gated concrete spillway is to be constructed on the right abutment, designed to pass a maximum flood of 180,000 cfs, The reservoir would have a total capacity of 420,000 acre feet, of which 370,000 acre feet would be useful storage. River outlet works would have a capacity of 2,500 cfs. Nugawela Power Plant

The main structures include a 20 foot diameter concrete lined pressure tunnel 23,500 feet long, surge tank, valve chamber, steel penstocks and a powerhouse. Four generating units with a total capacity of 120 I would be installed. The plant would operate under a head of 647 feet and average year generation would amount to 540 million KWH. An alternative design providing - 2 -

for an underground powerhouse and a 5 mile long tailrace tunnel is being studied and might provide a cheaper solution.

Primrose Diversion Works

These works consist of a concrete ogee weir across the Mahaweli Ganga, a sluice way, canal intake structures and skimmer weirs to prevent river bed- load from entering the canal. The weir would be 450 feet long with a maximum height of 30 feet above stream bed. The design flood of the weir is 180,000 cfs. Maximum diversion at Primrose would be 2,500 cfs, the project would be operated to pass the first 250 cfs of flow downstream the Mahaweli Ganga.

NOP Canal

The canal will start at Primrose and continue northw-ard for a total distance of 124 miles. The works include 119 miles of concrete lined channel, 5 tunnels with a total length of 2.8 miles, 8 siphons, 6 concrete chutes, a short length of covered conduit and a total of 266 principal structures, including culverts, bridges and turnouts.

From mile 0 to mile 10 the canal passes through difficult terrain and this section includes a 2 mile long tunnel and a 1400 feet long siphon across Hunan Oya. At mile 10 the water would be dropped 260 feet and the head would be used to develop 45 MW of power in the Ukuwela Power Plant. A concrete chutc and silting basin would be provided to bypass canal water.

The canal section from mile 10 to mile 25 includes a 1,000 feet siphon across Sudu Ganga. The Diggala Power Plant would be located at mile 25, also operating at a head of 260 feet, developing 45 MiW of firm power. The total canal section from mile 0 to mile 25 would have a maximum capacity of 2,500 cfs.

At mile 25, downstream of the power plant and concrete bypass chute, a structure would be constructed to divert a flow of maximum 500 cfs into the Sudu Ganga to be used for irrigation in the Elahera, Minneriya, Kantalai and Angamedilla areas.

The main canal will continue northward to the Anuradhapura District, with a capacity of 2,000 cfs to mile 50. From this point the canal would gradually diminish in size as water would be diverted into lateral canals.

At mile 43 a 240 feet drop would be utilized in the 33 iMl Lenadora power plant which also would be provided with a bypass concrete chute,

Three additional power plants are tentatively located at mile 61, 78 and 93 with an estimated total capacity of 17 NW.

Moragahakanda Reservoir

The Moragahakanda dam would be located on the Amban Ganga about one mile upstream of the existing intake works for the Elahera Canal, The reservoir -3- would be fed by the runoff from the 300 square mile catchment area of the Amban Ganga supplemented by the water diverted from the NCP Canal at mile 25, The reservoir would have a total capacity of 6,000 acre feet of which 420,000 acre feet would be useful storage.

The dam would consist of 3 separate rock and earthfill embankments and a concrete spillway structure designed for a maximum discharge of 215,,000 ofs. Total length of the embankments would be 3,330 feet and maximum height over the river bed would be 185 feet. The outlet works would have a capacity of 1,500 cfs.

The design of the dam is tentative pending further geologic investigations. A small power plant might also be considered in connection with the dam, but since generation mostly would be non firm it has not been included in the present scheme.

Lateral System

The lateral system for a major part of the service area would consist of a combination of existing and new channels to supply the large number of exis'k-, ing tanks and lands to be irrigated. For estimates of costs, plans have been prepared for a representative area of 31,000 acres, resulting in a cost of Rs.500/acre. For new areas the cost for the lateral system has been estimated at Rs.800/acre.

2eolog Geologic investigations have included detailed surface exploration and drillings on the sites of major structures. They indicate in general favorable conditions and do not point out any serious difficulties to be expected in connection with the construction of the proposed works. Adequate supplies of materials required for the construction have also been located.

Service Areas

The major area to be served is located in the Anuradhapura District of the North Central Province. This area is at present partially irrigated by a system of 15 larger tanks with a total capacity of about 370,000 acre feet and a large number of small tanks, The area theoretically served by these tanks amounts to 99,000 acres. With the limited local run-off these tanks can in an average year supply water for one crop during the rainy season and to a very restricted area also for a second crop druing the dry season. In a dry year, there is not even sufficient water for the full area during the rainy season.

With the supplemental water from the Mahaweli Diversion, the area supplied from the tanks could be extended to 155,000 acres with a firm supply for the irrigation seasons annually.

In addition, 30,000 acres of new land could be served by laterals fed directly from the NCP Canal and a further 30,000 acres could be irrigated by -4-

the return flows. Total irrigable area in the Anuradhapura District would therefore amount to 215,000 acres,

Flaws in excess of 2,000 cfs from the NCP Canal will supplement the waters of the Sudu Ganga and Amban Ganga and be stored in the Moragahakanda reservoir. It will be released for firm supplies to the existing Elehera- Kantalai and Angamedilla irrigation systems in the Polonnaruwa District, These systems include five tanks and the present area served irregularly amounts to 70,100 acres. With the supplemental water from Mahaweli, it can be extended to 110,000 acres of which 10,000 acres would be served from return flow.

Availability of Water

Operational studies of the scheme based on the period 1944-58 have been carried out. This period includes two periods of severe drought, 1944-45 and 1956-57. Tentative operating rules of the Nugawela reservoir were applied to provide flood protection tothe Kandy area and to obtain the maximum amount of firm power generation. Based upon reasonably computed water require- ments, the studies show that the stream flows and the structures proposed would provide sufficient water for the acreage to be irrigated during two seasons, March to July (Yala season) and September to January (Maha season). Irrigation requirements ranging from 8.5 acre feet/acre in dry years to 5 acre feet/acre in wet years have been used.

Cost Estimates

The total cost of the Scheme is estimated at Rs.1.2 billion of which some 50o would be required in foreign exchange ($250 million total including $125 million in foreign exchange). A review of the unit costs used for estimating purposes shows them to be some 25 to 30% higher than those quoted in the recent tenders for the civil works on the Norton Bridge Hydro Project.

Staging

The first stage of the Scheme would have to include the following works: Nugawela dam, Primrose diversion, NCP Canal, mile 0 to mile 10, Ukuwela power plant and NCP Canal mile 10 to mile 25. This will provide firm supply of water for the areas to be irrigated in the Polonnaruwa District and 45 MW of firm power. If required, the 45 NW Diggala power plant could be added to this stage.

The estimated cost of the first stage is: Total Foreign (mi.ll. Rs, ) First Stage 380.5 154.5 Diggala power plant 41.0 31.9 Total 421.5 186.4 ($88 million) ($39 million) -5-

The construction of this stage would require about 42 years; in addition 1L to 2 years would probably be required for detailed engineering, preparation of specifications and obtaining tenders.

The second stage would include the completion of the NCP Canal, laterals and the canal power plants. In the final stage the Moregahakanda dam would be constructed.

Allocation of Costs

Tentative estimates for allocation of costs are Rs. 631 million for irrigation and Rs. 572 million for power. Based on this estimate the capital cost for the power facilities works out to $450 per installed KW and 7 U.S. cents/IWH.

Benefits from irrigation

A principal feature of the proposed diversion project is that the exist- ing pattern of agricultural production in the project area will be stabilized and improved as a result of obtaining a firm water supply for both the Maha and Yala seasons. Thus while the cost of diversion works is relatively high, the irrigation phase of the project can be accomplished with relatively small additional investment in distribution works and also the associated costs for farm and community development will be small in comparison with such costs in the settlement of new areas. The farmers in the NCP area have had considerable experience in irrigation farming so that probable success of the project would be more certain than in completely new development areas.

Irrigation benefits have been estimated in the Mahaweli Diversion Project Study at about Rs. 80 million per year. The Operation and Maintenance costs. assignable to irrigation would probably not exceed Rs. 10 million so an annual return of Rs. 70 million on the Rs. 631 million allocated to irrigation, or about 11 per cent, would be very favorable.

Overall Benefit-Cost Ratio The report presents an overall benefit-cost ratio of 2.3 : 1; however, this appears to be high due to overestimation of benefits. A more realistic ratio would probably range between 1.6 and 1.8 to 1, which would still be a very favorable benefit-cost relationship. Appendix 3

WALANE GANGA BASIN

The Walawe Ganga Basin is located in the southeastern part of Ceylon. A general survey of this basin has been carried out by the Photographic Survey Corporation of Canada under the Colombo Plan assistance program. The report was completed in July, 1960.

The aim of the survey was to provide an inventory of geology, land forms, soils, land use, forest cover and hydrology and to make suggestions and recommendations about the future use of the land and water resources. The area covered in the survey amounts to 1,204 square miles and includes the Walawe Basin itself and two adjacent areas, the Kachigal Ara Basin and a part of the Malala Oya Basin.

The main stream of Walawe Ganga rises in the mountains west of the town Balangoda. It flows eastwards and emerges from the hills at Uggalkaltota where it turns sharply towards the south and flows through tha lowland plain for a distance of some 50 miles before discharging into the sea near Ambalantota.

The main upstream tributaries are Weli Oya and Belihul Oya.

Hydrology

Rainfall records for a period of 50 years from some 45 stations and daily stream flow records since 1942 from a station near Embilipitiya (21 miles from the mouth of the river) are available. Based on these records, the average annual runoff is estimated at 1.5 million acre feet at Embilipitiya, Q.8 million acre feet below the confluence of Weli Oya and Walawe Ganga and 0.5 million acre feet below the confluence of Belihul Oya and Walawe Ganga.

The report recommends that additional discharge gauging stations should be established and that the existing (two stations were established in 1957) should be equipped with automatic water-level recorders. Auto- matic recording rain gauges should also be installed at several stations to obtain more accurate data on duration and intensity of flood producing storms.

Development Program

The study makes it clear that the maximum power and irrigation benefits can only be obtained through a system of upstream reservoirs, diversion dams and supplementary structures. A four-stage program of development is proposed with the two first stages interchangeable in timing.

Stage 1 includes the construction of a 275 foot high dam on the up- stream Walawe Ganga creating a reservoir with 149,000 acre feet of live storage, a diversion tunnel and a power plant located on the north bank - 2 -

of Katupal Oya at the foot of a steep escarpment. The plant would under a head of operate between 900 and 1,000 feet. Firm output is estimated 27.5 million at KWH. Downstream from the power plant a 150 foot would be constructed high dam across Katupal Oya, creating a regulating reservoir with a capacity of 41.,000 acre feet. These works correspond to the Samanala Wewa project described in Appendix . Stage 1 would a diversion dam 4 also include on the Walawe Ganga below its confluence with Katupala Oya as well as necessary irrigation canals. Stage 2 includes a 191 foot high dam on Weli Oya, creating acre feet a 112,000 storage reservoir, irrigation canals and storage an increase in the capacity of the existing Hambegamuwa tank. of Only a small amount power could be developed at the Weli Oya dam site. Stage 3 includes possible storage dams on the two right bank tribu- taries, Kuda Oya and Rakwana Ganga, with associated irrigation canals. The flows of these tributaries have not been computed, and no field investigations have been made of possible dam sites.

Stage 4 includes a dam on the Walawe Ganga in the to provide region of Embilipitiya an adequate balancing reservoir for the irrigation coastal of the plain. This stage can only be developed after the upstream plans for the works have been established in more detail and possible it becomes to evaluate the quantity of water available in of the lower region the river. The Uda Walawe project described in Appendix corresponds 5, which to Stage 4, was developed before the Canadian study available. became

The total area which possibly could be irrigated is estimated at 230,000 acres, based on topographical studies. With the proposed develop- ment plan, sufficient water should be available to serve this area. The survey concludes that the possible development looks sufficiently promising to justify more detailed studies. This would in particular include the evaluation of additional information on river discharges Walawe Ganga of and its tributaries to be obtained from the gauging recommended, detailed stations investigations of possible dam sites, topographical surveys of lands to be irrigated, land classification survey and opera- tional studies to establish the necessary coordination of water releases for power production and irrigation. Appendix 4

SAMANALA WEWA PROJECT

A reconnaissance report on this project was prepared by Tudor Engineering Company in 1958 and a more detailed feasibility study was carried out by Hydrotechnic Corporation and Engineering Consultants, Inc., in 1959. The studies were in both cases financed by ICA.

The feasibility report is limited to the development of a plan to utilize the waters of the upper Walawe Ganga on the premise that the water eventually would be used for irrigation purposes, but the irri- gation features did not form a part of the study, and only rudimentary information was available on the lands to be irrigated.

Proposed Project

After evaluating a number of possible alternatives, the U.S. consultants propose the following scheme as the most suitable for the development of the upper Walawe Ganga. A 353 feet high earth fill dam would be constructed at Samanala immediately downstream of the con- fluence of Walawe Ganga and Belihul Qya. Total reservoir capacity is estimated at 340,000 acre feet of which 118,600 acre feet is useful storage. Water would be diverted through an 8,870 feet long tunnel with a minimum capacity of 566 cfs to a forebay reservoir on the Diyawini Oya with a capacity of 12,56 0 acre feet. The forebay dam would be a rock fill structure, 600 feet long and with a height of 128 feet above the stream bed, and with adjacent dikes. A 1,300 feet long canal would connect the forebay with the penstocks leading to the power house. This would be equipped with four generating units with a total capacity of 120 MW.

Included in the proposed project is also 88 miles of 132 KV trans- mission lines to Laksapana and Galle and associated substations.

To serve a tentative area of 40,000 acres a re-regulating reservoir would be required on the Katupal Oya downstream of the power plant. The capacity of this reservoir has been estimated at 51,200 acre feet including 32,000 acre feet of useful storage.

Total project costs excluding the re-regulating reservoir are esti- mated at Rs. 209 million ($43 million) of which Rs. 109 million ($22.5 million) in foreign exchange. This estimate includes design, engineering, overhead and some 15% contingencies, but not interest during construction. A tentative allocation of costs estimates Rs. 157 million for power and Rs. 52 million for irrigation.

Hydroloy

Stream flow records were only available for a period of 14 months. Monthly discharge values for a 25 year period were therefore completed from available rainfall records. Average annual run-off at the Samanala dam site was estimated at 435,000 acre feet and at the forebay site at 454,000 acre feet. -2-

Geology

The study included surface investigation of the project area and preliminary drillings at the dam sites and tunnel alignment. Conditions are in general favorable. Suitable deposits of materials for the dam construction were also located.

Power Generation

Average annual generation of firm power is estimated at 349 million KOH, corresponding to a capacity of 40 MW. A substantial part of the proposed installation would therefore serve for peaking.

Irrigation Department Renort

This report was prepared in September 1960 by Mr. Kothare. It questions the proposals made by the U. S. consultants and argues that the dead storage provided in the Samanala Wewa reservoir is excessive. He proposes to lower the dam by 23 feet, construct the diversion tunnel as a pressure tunnel and lower the invert level by 115 feet and leave out the forebay reservoir. The length of the tunnel would be increased to 18,500 feet. He also reduces the capacity of the tunnel to 424 cfs and the firm power capacity to 26.3 MW. No comparative cost estimates are given but it is claimed that this alternative scheme would be better adaptable to a tentative overall development of the Walawe Ganga Basin. The reasons for this are not given. Appendix 5

UDA WALAWE PROJECT

A preliminary report has been prepared on this project by Engineering Consultants, Inc., under a contract with the Ceylonese Government. The report was completed in November, 1960.

The terms of reference of the study were limited to investigating the feasibility of construction of a dam on the Walawe Ganga at Uda Walawe, some 32 miles from the mouth of the river. The water would be used for irrigation of some 50,000 acres and, if feasible, also for generation of power.

The dam proposed would consist of a 7,700 feet long earth embankment and a concrete spillway and a power house. The maximm height over the stream bed would be 66 feet. A single 2,500 KW generating unit would be installed, but the capacity would have to be firmed up by a 1,200 1W4 diesel plant unless a connection with the central grid is provided.

The reservoir would have a useful capacity of 30,000 acre feet. The total cost is estimated at Rs. 36 million ($7.5 million).

It is understood that the Irrigation Department has requested the consultants to revise the proposed project to provide for more storage capacity and to consider other possible dam sites. Investigations are presently being made on a site further downstream near Embilipitiya. Appendix 6

KELANI GANGA PROJECT

late in 1959, the Ceylonese and Soviet Governments entered into an Agreement on Economic Cooperation and Technical Assistance for the study of a scheme of flood control and water resources development of the Kelani Ganga. The work was assigned to Giprovodkhoz, the Design and Research Institute for Land and Water Development of the Ministry of Agriculture of the Soviet Government. The agreement provides for the study of a multi- purpose development for flood control, power production, development of irrigation in the Kelani Basin and also for the diversion of the Kelani waters to the north into the dry zone for irrigation. The primary purpose to be served by the development scheme is flood control.

Under the conditions of the contract, the operations are to be carried out in two stages. The first stage consists of the collection of data, field reconnaissances, preliminary studies and investigations, which work is to be done jointly by the Soviet and Ceylonese specialists in Ceylon. The second stage includes the preparation of the comprehensive plan and re- port, which work is to be done by the Soviet specialists with the participa- tion of the Ceylonese specialists in Moscow.

Soviet technicians arrived in Ceylon in February, April and July, 1960. Totalling eight in number, they completed their planned field work, collec- tion of data, etc., and returned to Moscow at the end of October. Giprovodkhoz prepared an "unedited report on contemplated measures" which consists of a very preliminary general discussion of the various alternatives that will be considered for flood control, power and irrigation, without sketches, cross sections, capacities or estimates of cost. No conclusions are reached. The report is accompanied by a map showing the general scheme of diversion. We are informed that the preparation of their plan and report will be completed in Moscow in about one year.

The "unedited report" discusses the measures that will be considered for control of floods by means of levees alone and by means of a combination of levees and detention reservoirs. The levee system scheme contemplates the construction of bunds either along the existing channel or along an im- proved channel increased in capacity by widening, by cut-offs and by deepening. It envisages the locations of levees at such distances apart and to such heights that the design flood will flow safely into the lower reach of the river.

The scheme of a combination of levees and reservoirs will be considered by three alternatives, in all three of which the lower 25 mile reach of the river to the mouth would be protected by a levee system. The first alterna- tive will consider a large detention reservoir in the middle reach of the river, the second a system of detention reservoirs in the upper reaches of the river and the third, a system of reservoirs in both the upper and middle reaches.

Hydroelectric power development will consist of the construction of power stations at the river regulation reservoirs. It will take into considera- - 2 -

tion the existing power developments and the developments proposed on the Maskeliya Oya and Kehelgamu Oya. Itis stated that the additional capacity of the Kelani scheme might possibly amount to a total of 70,000 KW.

Existing irrigation in the Kelani Basin will be benefitted by in- creased supplies and by protection against floods inundating the fields. The development of new irrigation is said to be limited.

The diversion of surplus waters from the Kelani Ganga Basin into the dry zone to the north for irrigation will be considered by means of either a gravity canal of 1300 cusecs capacity and about 75 miles in length to irrigate 100,000 acres or a canal with pumping stations having a length of about 100 miles and a capacity of 2900 cusecs to irrigate 200,000 acres.

The date of the arrival of the Ceylonese specialists to participate in drawing up the "Kelani Scheme" is tentatively set at the beginning of the second quarter of 1961.

In the GIPROVODHOZ "unedited report", except for a statement that the design flood is 250,000 cusecs, there is no discussion of the extent of floods and flood damages, since the Ceylonese technicians were requested to prepare a paper on this subject for consideration in Moscow. Such a report, entitled "Economic Condition of Flood Control and Utilization of Water Potential of the Kelani Ganga" was completed by the Irrigation Department, Ceylon, in November, 1960. This report states that minor floods occur at least once each year and major floods have occurred 23 times since 1883, Dangerous floods occurred in 1913, 1930, 1940 and 1947, the maximum flood of record being 220,000 cusecs at Colombo and occurring on August 17, 1947. After the 1913 flood, a flood protection scheme was constructed for the Colombo area which was later improved by twice increasing the heights of bunds after the 1930 and after the 1947 floods. The existing flood protec- tion scheme will give protection from a flood of the size of the 1947 flood but will not adequately protect the area against higher floods. The 1947 flood inundated 17,000 houses in 16 villages in the Colombo area, rendering 267,500 people homeless. The total estimated damages were Rs. 10 million, of which about Rs. 8 million were direct and Rs. 2 million indirect damages. Appendix 7

MASEELIYA OYA PROJECT

A feasibility engineering study on the Maskeliya Oya power develop- ment has been prepared by Hydrotechnic Corp. and Engineering Consultants, Inc., under a contract between ICA and the Ceylonese Government. Their report was completed in May, 1960. The study started with an investiga- tion of the single stage Seven Virgins project proposed by the UNTAA Power Adviser, Mr. Pfeiffer. In the course of the study, it was found that a three stage development would have technical and economical advantages. The proposed project would consist of the following works.

Mousakelle Dam

The dar located on the upstream Maskeliya Oya would be a 600 feet long earth fill structure with a maximum height above the stream bed of 132 feet. The spillway would be of the "morning glory" type, uncontrolled and connected to the diversion tunnel to be used during construction. The reservoir would have a capacity of 85,000 acre feet with 80,000 acre feet useful storage. The reservoir would inundate 1,600 acres of tea plantation land, two villages and ten miles of existing roads.

Theberton Power Plant

The plant would be located 3.5 miles downstream of the Mousakelle Dam. The operating head is 890 feet. Water would be conducted from the dam outlet structure through a 4,400 feet long steel pipe line and then through a 14,000 feet long open canal with three short tunnel sections into a forebay with a capacity of 16 acre feet. Steel penstocks would connect the forebay with the powerhouse which would be equipped with two 11,250 KW generating units.

Laksarana Power Plant (Extension)

A low diversion dam 430 feet long of rolled earth with a concrete spillway would be constructed across the river immediately below the Theberton plant. The regulating reservoir would have a capacity of 580 acre feet. Water would be conducted from the outlet through 13,600 feet of open canal and 700 feet of tunnel to a forebay with a capacity of 20 acre feet. This would be connected to the power house with three steel penstocks. The power house would be an extension of the existing Laksapana plant. Three 25,000 XW generating units would be installed. Operating head would be 1,500 feet.

Morahena Power Plant

A rockfill diversion dam with a concrete spillway would be construc- ted across the river below the Laksapana plant. The dam would be 410 feet long with a maximum height of 61 feet above stream bed. The capacity of the reservoir would be 33.4 acre feet. From the outlet, the water would -2 - be conducted through 9,000 feet of open canal and a 1,700 feet long con- crete siphon into a forebay with a capacity of 10 care feet. Two steel penstocks would connect the forebay with the power house which would be equipped with two 25,000 jW generating units. The operating head would be 578 feet.

The location of the Morahena plant was chosen under the assumption that a multipurpose reservoir would at some future date be constructed at Broadlands on the Kelani Ganga below the confluence of the Maskeliya Oya and the Kehelgamu Oya. More recent information indicates that this dam would not be constructed because the unfavorable conditions at the dam site would make it very expensive and a substantial area of tea plantations would be inundated. The cost of this scheme, therefore, would be excessive in relation to the benefits which could be obtained.

The design of the Morahena plant is therefore being modified at present. The site would be moved one mile further downstream and the head would be increased to 900 feet and the installed capacity could be increased to 80,000 EW.

As this plant would utilize the tailrace water of the existing Laksapana plant in addition to the flow in Maskeliya Oya, it could be operated without the upstream storage at Mousakelle. Under these con- ditions the firm capacity would be 36,000 KW and with back up of the Grandpass thermal plant an installed capacity of 50 KW would be justi- fied. Average annual generation under these conditions would be 270 million KWH.

Transmission Lines

The consultants also propose various transmission lines with associated substations but have not taken into consideration the lines to be constructed by DGEU in connection with the Norton hydro plant. This part of the report, therefore, would have to be completely revised.

Hydroloa

The estimate of monthly run-off values at the various dam sites has been based on 25 years of rainfall records. Actual flow measurements were only available for short periods. Average annual discharge at Mousakelle has been estimated at 230,000 acre feet and at Morahena at 332,000 acre feet. For the detailed design the hydrology of the project would have to be restudied using the additional data provided by the gauging stations now installed.

Geology

A preliminary investigation has been made of the geology of the area including drillings on the sites of the major structures. The studies - 3 - indicate generally satisfactory conditions. More comprehensive studies would be required as a basis for the detailed design.

Estimated Costs

The costs based on the original design of the Morahena plant have been estimated as follows:

Foreign Local Total (Million Rs.)

Mousakelle Dam 7.1 24.4 31.5 Theberton Plant 17.3 11.3 28.6 Laksapana Plant 50.0 31.7 81.7 Morahena Plant 31.7 20.0 51.7 Construction camps and equipment

108.8 92.1 200.9 In million $ 22.7 19.3 42.0

Transmission lines (mil.Rs.) 27.7 6.8 34.5

Unit cost for the total installation on 147.5 MW would amount to $240/EW.

The cost estimate includes design, engineering, overhead and about 20% for contingencies for civil works and 10% for equipment. Interest during construction has been excluded.

A preliminary estimate has also been prepared by DGEU for the Mora- hena plant at the new location and 50 MW installation. It amounts to Rs. 49 million including Rs. 28 million in foreign exchange. This would correspond to $200/W installed. In this estimate 50% has been added for the increased length of the intake canal and a further 30% to cover the extra cost of a tunnel as against the open channel proposed in the original plans.